With conventional full complement roller bearings with no cage or retainer, a full complement of rollers are coated with grease and charged inside an outer ring to be retained inside the outer ring by adhesion of the grease. The full complement roller bearings constructed as stated earlier has a major problem in which the rollers are liable to fall away apart from the outer ring while in handling because of less in retention or retentive faculty of grease.
A full complement of rollers is known as shown in, for example in Japanese Publication No. H46-9082 in which a retaining material charged around the rollers solidifies to join together the rollers. The rollers are disposed circularly and joined together with adhesion of the retaining material which fills in the gaps or interstices among the rollers. The retaining material is mainly composed of synthetic resin blended with inorganic solid lubricant. Blending the solid lubricant is to give the retaining material more lubricating performance.
Another prior roller bearing is disclosed in, for example Japanese Laid-Open Patent Application No. H07-238 940 in which many rollers are arranged over a race lying on an inside circular surface of an outer ring and a solid lubricant is charged around the rollers to join the rollers together with keeping individual rollers in place at preselected intervals spaced away from each other. The solid lubricant is a lubricating composition of a blend of ultrahigh molecular weight polyolefin with grease.
International publication No. WO 2006/051 671 discloses a thermoreversible gel-like lubricating composition composed of a mineral oil and/or synthetic liquid lubricating base oil, and a bisamide and/or a monoamide. The composition normally is in a form of semi-solid gel as with grease, but turns into homogeneously melted status with no deposition of foreign materials when encountering a local high-temperature area in for example a sliding contact site. The composition dissolved as stated earlier has much energy-saving performance based on excellent low frictional characteristics. Thus, the thermoreversible gel-like lubricating composition has the lubricating performance which wouldn't be expected in grease.
In Japanese Laid-Open Publication No. 2011-26 432, there is disclosed a lubricant composition and a rolling-contact bearing using the same. The lubricant composition is made semisolid with using gelling agents to increase the fluidity and fluid-restoration reversibility. The rolling-contact bearing using the lubricant composition prepared as stated earlier is improved in prolonged service life and less in torque. With the prior lubricant composition, base oil is thickened with only using amino acid-based gelling agent and benzylidene sorbitol-based gelling agent. The mass ratio between amino acid-based gelling agent and benzylidene sorbitol-based gelling agent is 20-80%:80-20%. The rolling-contact bearing using the lubricant composition is composed of an inner ring, outer ring and many rolling elements disposed between the inner and outer rings for free rotation. The lubricant composition is packed in an inside space defined between the inner ring and the outer ring.
Meanwhile, grease used in the full complete roller bearing isn't intended to just hold or retain the rollers inside the outer ring, but envisioned mainly serving lubricating function for the rollers. With the prior roller bearing in which a full complete of rollers are retained inside the outer ring with adhesion of grease applied over the inner surface of the outer ring, there still remains a major challenge in which since grease is inferior in retention or retentive faculty, the rollers are liable to fall away apart from the outer ring on assembly of the outer ring with a full complement of rollers into the inner ring or the shaft, or while in transit, for example while in assembling operations for shock absorbers, swing arms and so on, thereby resulting in obstacles to easy assembly and transit operations. With the roller bearing constructed as stated earlier, a full complement of rollers is retained inside the outer ring with usually getting a solid lubricant to function as the retainer. The greater is the force of the solid lubricant to retain the rollers, the greater is the torque needed to actuate the roller bearing. This increase in torque is adverse to operations in the roller bearing and, therefore, the solid lubricant poses another challenge.